IMO MARINE ENVIRONMENT PROTECTION COMMITTEE 60th ...

MEPC 60/4/7 - 4 -
turbine main engines. Therefore, in obtaining the baseline for gas tankers, steam turbine ships in
LRFP should be excluded from the input data in order to keep consistency with the annex to
MEPC.1/Circ.681.
16 Refrigerated cargo carriers, which would be categorized as general cargo ships if the
present categories in the annex to MEPC.1/Circ.681 are followed, should be treated as a separate
ship type. Refrigerated cargo carriers generally navigate at a higher speed than general cargo
ships due to the service requirement to reduce the transport time of fresh foods, thus making their
baseline deviate considerably from the baseline for general cargo ships. A rationale for such a
separate ship category is provided in annex 2 to this document.
17 To ensure a uniform interpretation, a table presenting the association of ship types given in
the annex to MEPC.1/Circ.681 compared to the ship types given by the LRFP Stat codes is shown
in annex 1 to this document. Table 2 in annex 1 lists the LRFP ship types which clearly should not
be used when calculating the baselines for the specific ship types in the annex to MEPC.1/Circ.681,
e.g., ships built for sailing on the Great Lakes, bulk/oil carrier (OBO), landing craft.
Blank data entries
18 For some LRFP ships, some data entries may be blank or contain a zero (0). Datasets
with blank power, capacity and/or speed data should be removed from the baseline calculations.
For the purpose of later references, the omitted ships should be listed.
Speed
19 The definition of speed in the annex to MEPC.1/Circ.681 is: “V ref is the speed, measured in
nautical miles per hour (knot), on deep water in the maximum design load condition (Capacity)
as defined in paragraph 3 at the shaft power of the engine(s) as defined in paragraph 5 and
assuming the weather is calm with no wind and no waves. The maximum design load condition
shall be defined by the deepest draught with its associated trim, at which the ship is allowed to
operate. The condition is obtained from the stability booklet approved by the Administration.”.
20 The condition for the LRFP service speed information is not clear. Normally, the service
speed of a ship is given at 85-90% MCR combined with a sea margin of 10-15%. This was
indeed the rationale for defining the power (P ME(I) ) for calculation of the attained index as 75% of
the rated installed power (MCR). Accordingly the service speed information in LRFP will be the
most accurate speed to use as V ref when computing average index values and baselines.
Capacity
21 The capacity for each ship type is defined in the annex to MEPC.1/Circ.681.
Installed power
22 The installed main power P ME(i) and the required auxiliary power P AE are defined in the
annex to MEPC.1/Circ.681. For cargo ships with a main engine power of 10,000 kW or above,
the P AE should be calculated according to paragraph 2.5.6.1, and for cargo ships with a main
engine power below 10,000 kW, the P AE should be calculated according to paragraph 2.5.6.2.
For passenger ships with conventional propulsion systems, the P AE value should be estimated by
the consumed electric power (excluding propulsion) in conditions when the ship is engaged in a
voyage at reference speed (V ref .) as given in the electrical power table divided by the weighted
average efficiency of the generator(s).
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